If you’re using Adobe InDesign to lay out your book, there’s a little function under the File menu that you should be aware of. It’s called PreFlight.
Selecting Preflight gives you a detailed rundown of the condition of your document from a pre-press point of view. It helps you spot font problems, potential color-mode errors (like RGB images), and more. Here’s the top-level report from Evil Inc Annual Report Vol. 6:
Fonts: 12 Fonts Used; 0 Missing, 0 Embedded, 0 Incomplete, 0 ProtectedLinks and Images: 531 Links Found; 0 Modified, 0 MissingImages: 0 Embedded, 0 use RGB color spaceColors and Inks: 4 Process Inks; 0 Spot InksCMS is ON
It can even help you track down errant RGB files. Just click on the pertinent area on the left of the dialogue box to get an expanded run-down. For example, below, I clicked on Links and Images:
The main dialogue box now gives a complete break down of all of the image files used in the document, grouped by color mode, file type, etc.
Issues like RGB files, spot inks and broken fonts are immediately flagged for you at the Summary level.
It’s a very useful tool that even very experienced designers sometimes overlook completely.